The present invention relates to a speaker system including at least one reflector for adjusting the directional characteristics of the speaker to increase the dispersion of sound at the higher frequencies and, more particularly, a system which has a pair of such reflectors.
A typical speaker system incorporates a moving element that translates electronic signals received from an amplification source into sound pressure waves by moving air with a diaphragm or like moving element that vibrates in sympathy with the incoming signals. As all musical sounds and speech is made up of varying frequencies, this translation of the electronic signals into the movement of air must also occur at varying frequencies. As the frequency produced increases, the sound that is produced by the speaker becomes more and more directional in nature; at frequencies above 250 Hz, this directional phenomena becomes noticeable. Indeed, most tweeters are so directional that the sound produced at these frequencies (above 4,000 Hz) is lost at anything more than 15.degree. off the central axis perpendicular to the front of the tweeter (that is, the sound is limited to a 30.degree. field). The higher frequencies are produced more and more in a plane that is 90 degrees (i.e., transverse or perpendicular) to the vibrating plane of the moving element or diaphragm of the speaker.
To help improve this limited dispersion at the higher frequencies, most speakers have a domed or conical shaped moving element. However, the movement imparted to this dome is still in a plane that is 90 degrees form the surface plane of the speaker. In the case of horn-type speakers, most horns have a very large flare starting from the moving element and expanding to the opening of the horn. This flare is, however, quite deceptive in that high frequencies will not follow a curve. As a rule of thumb, in order to hear the higher frequencies produced by a horn-type speaker, one must be able to actually see the moving element.
Typically dispersion becomes more and more narrow with higher frequencies. A problem arises in that the listener must be located within this narrow dispersion area or "sweet spot" in order to hear the complete content of the sound being produced. If not located within this "sweet spot", higher frequencies (those above 250 Hz) become muffled, and very high frequencies (those above 4,000 Hz such as cymbals, or sibilants such as the sss and ttt sounds, and the overtones of all musical instruments) are lost to the listener. For this reason, most concerts are performed with the system in mono or monaural condition, where the same sound emanates from speakers placed to the left and right of the performance area. If a stereo performance were desired, only those listeners who were equally within the "sweet spot" of both the left and right speakers, would benefit. For most, the sound coming out of the left speakers would be a mystery to those on the right, and vice versa. The conventional solution is to use many mid and high frequency speakers, pointed in multiple directions, in order to allow the entire audience enjoy full fidelity from both left and right outputs. This is extremely expensive to achieve, and frequently it is not possible or economical for the average performing environment. Thus, the need remains for a practical and economical way to enlarge this "sweet spot" so as to allow everyone to enjoy full fidelity sound regardless of their position.
U.S. Pat. No. 4,701,951 discloses an improved stereophonic imaging system with two stand-alone cabinet units. Sound baffles are symmetrically arranged about a common vertical plane to emit directly radiated sounds while individual panels with cylindrical, convex reflecting surfaces are disposed with axes parallel to the common plane at variable distances from, and at variable angular orientations to, the common vertical plane, thereby to redirect energy emanating from the transducers as reflected secondary sound. The reflected sound blends together with the directly radiated sound to provide a coherent central image with improved definition and fidelity. The stereophonic system requires at least two stand-alone cabinet units or speaker enclosures rather than just one. Additionally, the reflecting surfaces reflect the sound only inwardly towards the common plane between the cabinet units (i.e., towards the other cabinet unit) rather than outwardly to both lateral sides of each cabinet unit. As a result, the "sweet spot" is necessarily relatively narrow.
Accordingly, it is an object of the present invention to provide an adjustable speaker system.
Another object is to provide such a speaker system which incorporates an adjustable reflector to reflect impinging sound.
A further object is to provide such a system with two independently adjustable reflectors wherein the adjustable reflectors redirect impinging sound laterally to both respective sides.
It is another object of the present invention to provide such a system which is inexpensive to manufacture, use and maintain.